Cancer can be defined as sporadic, familial, or hereditary. This classification can assist nurses in identifying individual family members at risk for cancer and developing a plan for cancer screening, prevention, and risk reduction. Distinguishing the type of cancer can also help determine whether genetic testing is appropriate for individuals in a particular family:
Sporadic cancers (SCs) account for the majority of cancers diagnosed in the United States. SCs occur due to errors of DNA replication in genes that normally function to promote cell growth and development, and typically develop after the age of 60.
Familial cancers are characterized by an increase in the number of cancers within a family; however, the pattern of cancers is not consistent with a hereditary cancer syndrome. Unaffected, close relatives are considered to be at increased risk of developing the cancers seen within the family when compared with the general population.
Hereditary cancer syndromes (HCSs) are attributable to mutations in specific genes that are inherited from either parent in an autosomal dominant (AD) or recessive pattern. Only about 5% to 10% of all cancers are hereditary. Individuals who inherit a highly penetrant cancer susceptibility gene are likely to develop cancer within their lifetime. The challenge for busy healthcare providers is to identify high-risk individuals and to assure access to comprehensive risk assessment services.
Identifying Hereditary Cancer Risk
A three-generation pedigree of both the maternal and paternal lineage is constructed to identify HCSs. First-degree relatives (parents and siblings) share 50% of their genes; second-degree relatives (aunts, uncles, and grandparents) share 25% of their genes; and third-degree relatives (cousins) share approximately 12.5% of their genes. The pedigree consists of the family members (both affected and unaffected), types of cancer, and age of the cancer diagnosis. Other signs of an HCS include: For example, a 30-year-old woman whose mother developed ovarian cancer at age 45 could be at high genetic risk of developing cancer because early ovarian cancer is a
